Think for a moment about what makes for an appealing website. Is it a simple, uncluttered design? Snazzy graphics? Videos and animation?

Those attributes all have one feature in common: they are visual. The web is something we browse, looking for information to read, icons to click on, videos to watch. The one thing we don't normally associate with the web is sound, even though it is a vital part of everyday communication. As musician Andrew Peggie puts it: "The web is a silent place."

Mr Peggie has conducted research into 450 company websites and found that just under half included sound, most often as part of a video or animation. Only 12 showed excellent examples of "considered and effective" usage. He believes sound is often an afterthought on websites: "Web designers have very strong visual backgrounds, so they don't have the same awareness of how music can work as they do with the visual elements."

But does it matter? Web users commonly want to find information quickly. Does adding sound to a website increase its appeal or get in the way?

Mr Peggie is on the advisory board of Sound Strategies, which advises companies on the use of music to support their brands. He believes that, used effectively, sound can create a much richer experience for the user. "Where designers have thought about how the music will fit with the overall experience of the site, the whole becomes greater than the sum of the parts," he says.

A wealth of research demonstrates the powerful connection between music, emotion and memory, according to Michael Spencer, managing director. Some companies have created associations between the brand and a piece of music - few of us can hear Delibes' "Flower Duet" without thinking about British Airways. But too often, he says, music is an afterthought: "It's used as an add-on like a vase of flowers on the table to make the room look more striking rather than as an integral tool for positioning."

But how much impact does sound really have on the user? "For premium categories such as sportswear, fashion and automotive, music is essential to create theatre and drama. Without the music the website doesn't build excitement," says Ajaz Ahmed, co-founder and chairman of web design agency AKQA.

Mr Ahmed has worked with clients such as Nike and Fiat to create websites rich in both sound and animation. The Fiat website ( www.fiat.co.uk ), for example, offers a visual and auditory "guided tour" of its latest models, aiming to replicate a real-life experience.

While many people who visit websites are what Mr Peggie calls "convergent" users (they look for a specific piece of information), a site that uses sound effectively can, he believes, turn them into "divergent" users - people who stay longer and make return visits.

Not everyone is convinced. Thomas Herbert, product manager at web host Hostway, argues that music is often intrusive, and other forms of sound - such as the animated customer service representative who "greets" you on some websites - "gimmicky".

Curtis James, managing director of Audemos, a company providing audio for websites, says a little sound goes a long way: "Music can be part of a customer's sonic brand, but it's about using it sparingly. You need to know when enough is enough."

Where audio can clearly add value is in podcasting, particularly for knowledge-based organisations such as law firms or universities.

Within weeks of launching a podcast in 2005, the scientific journal Nature was achieving 40,000 downloads a week. Yet many companies have seized on podcasting because it's easy to do, says Mr James, while they neglect to think whether it adds value: "The most important thing is the story. If [the company] has got something to talk about it's worth their looking into it. Often with podcasts there's not much story going on; there's nothing going on that couldn't have been delivered using text."

Whether audio more generally has something to offer the user is a harder question to answer. Mr Spencer cites the work of academic Howard Gardner, who identified three main learning styles: visual, auditory and kinaesthetic. Most people, argues Prof Gardner, prefer one style over the others. By setting the visual style above the rest, Mr Spencer suggests, companies are neglecting a large body of people who respond better to music and speech than text and pictures.

The distinction is not universally accepted, though. As Mr Herbert puts it, it depends on whether you believe "the internet needs to be some big experience, or you just want to get the information."